Method and apparatus for folding sheet material



Jan. 9, 1968 c. H. HEIGL I 3,36

METHOD AND APPARATUS FOR FOLDING SHEET MATERIAL Filed Nov. 22, 1965 INVENTOR. CARL H. HE/GL A T TORNE Y3 United States Patent 3,362,705 METHOD AND APPARATUS FOR FOLDING SHEET MATERIAL Carl H. Heigl, Bay Village, Ohio, assignor to Harris- Intertype Corporation, Cleveland, Ohio, a corporation of Ohio Filed Nov. 22, 1965, Ser. No. 508,956 12 Claims. (Cl. 270-68) The present invention relates to the folding of material, and more particularly relates to a method and apparatus for folding sheet-like material.

A principal object of the present invention is the provision of a new and improved method and apparatus for effectively folding material at a predetermined fold line and in which the material is electrostatically secured to members which move to effect the folding thereof.

Another object of the present invention is the provision of a new and improved method and apparatus for folding sheet material and in which the material is positioned on cylindrical surfaces and an electric field is established to cause the material to be held on the cylindrical surfaces and the cylindrical surfaces are then moved so as to fold the material.

Another object of the present invention is the provision of a new and improved sheet folding apparatus including a pair of oppositely rotating cylindrical surfaces which are spaced to form a nip therebetween and wherein a sheet of material is positioned on the cylindrical surfaces in sliding relationship, and then spaced portions thereof are electrostatically secured to the cylindrical surfaces and move through the nip in response to rotation of the cylinders to fold the sheet material along a line between the spaced portions.

Another object of the present invention is the provision of a new and improved sheet folding apparatus, of the type described in the next preceding object, and which includes a switch means which is operative to establish the electric field when the sheet is positioned on the surfaces.

Further objects and advantages of the present invention will be apparent to those skilled in the art to which it relates from the following detailed description of the prefer-red embodiment thereof made with reference to the accompanying drawings forming a part of this specification and in which:

FIG. 1 is a diagrammatical elevation view of a sheet handling apparatus embodying the present invention;

FIG. 2 is a view similar to FIG 1 illustrating an operative condition of the apparatus; and

FIG. 3 is a view similar to FIG. 1 illustrating still another operative condition of the apparatus.

The present invention provides a simple and effective method and apparatus for folding material along a predetermined fold line. Although a sheet folding method and apparatus embodying the present invention is particularly useful in the folding of sheets of paper and is described in reference to the handling of such material, it should be apparent that a method and apparatus embodying the present invention is well adapted to fold other types of material as well.

-In the illustrated and preferred embodiment a sheet folding mechanism is utilized to fold material in sheet form. The sheet folding mechanism 10 includes a pair of movable surfaces 12 and 13 and means 14 spaced from the surfaces 12 and 13 and operable to cause spaced portions of the sheet to be secured to the surfaces so as to move with the surfaces. The surfaces 12, 13 move so as to effect a folding of a sheet secured thereto.

The movable sheet supporting surfaces 12 and 13 comprise the peripheral surfaces of cylinder members 15 and 16, respectively, and are preferably smooth uninterrupted surfaces. The cylinders '15 and '16 are supported for rotation in suitable bearing members, not shown, and are driven in opposite rotational directions by a suitable driving mechanism, which is shown schematically and indicated by the reference character 18. In the illustrated embodiment the cylinders 15 and 16 are of the same diametrical size and are rotated at the same speed in opposite direction; however, it should be apparent that the cylinders may be of different diametrical sizes provided that their surface speeds are the'same.

.The cylinders 15 and 16 are preferably positioned so as to define a material folding nip 17 there/between. The spaced portions of the sheet material when secured to the cylinders move toward each other and into the nip 17. When in the nip, the spaced portions of the material face each other and thus the material is folded. The folding, of course, occurs along a fold line 30a intermediate the portions of the material which are secured to the cylinders. Alternatively, the cylinders 15, 16 could be spring loaded together with the spring allowing the rollers to move apart when material advances therebetween.

The means 14 which secures the spaced portions of the material to the cylinders 15, 16 is positioned above the cylinders 15 and 16, as viewed in the drawings and comprises electrostatic means. The electrostatic means includes a conductive member 20 which extends axially along the cylinders and two rows of ionizing needles 21 electrically connected to the member 20 and which extend toward the uppermost portions of the peripheries of the peripheries of the cylinders 15 and 17, respectively. The ionizing needles are aligned and located at longitudinally spaced points along the electrostatic means 14. The ionizing needles 21 are electrically connected to the conductive member 20 which is connected to one side of a high voltage source 22. The other side of the source 22 is grounded such that when a switch 23 in the circuit is closed, an electric field is developed between the electrostatic means 14 and the cylinders 15 and 16, which are grounded, as is Well known.

When the electrostatic means is energized, the ionizing needles 21 cause the air adjacent the needles to ionize due to the establishment of a potential difference between the needles and the grounded cylinders. The needles 21 propel ions toward the cylinders 15 and 16 and electrostatically charge the portions of the sheet 11 which are in engagement with the rotating cylinders and cause these portions of the sheet to be attracted to the surfaces 12 and 13. This attraction causes the sheet to cling to the cylinders and relative motion between the sheet and the surfaces 12, 13 is resisted. As a result of this attraction, a driving engagement between an area of the sheet and each of the cylinders is established and the electrostatically charged portions of the sheet 11 are moved toward each other by the cylinders and carried through the nip 17 in facing relation, as illustrated in FIGS. 2 and 3. When a medial portion 30 of the sheet is carried through the nip, a longitudinal crease 30a is formed in the paper due to the compression of the sheet between the cylinders at the nip, the remainder of the sheet will, of course, be drawn through the nip ina well known manner and the sheet ultimately will be discharged in folded form due to the rotation of cylinders. The electrostatic charge on the sheets is rapidly dissipated as the sheet moves out of the electric field, so that when the sheet is passed through the nip 17, there will no longer be an electrostatic attraction between the cylinders and the sheet.

In the illustrated embodiment the switch 23 between the electrostatic means 14 and the high voltage source 22 is shown positioned to cooperate with a rotatable cam member 28. The cam 28 is driven in timed relation with a feed mechanism, not shown, to actuate the switch 23 and close the circuit when the sheet 11 has been positioned relative to cylinders 15, 16 prior to folding thereof. In the illustrated embodiment, the cam member 28 includes a dwell portion 23a for maintaining a charge on portions of the sheet while the sheet feeds through the nip 17. Continued rotation of the cam opens the circuit when the sheet has passed through the nip and prior to feeding of a following sheet onto the table. In the illustrated embodiment the circuit which connects the electrostatic means 14 and the voltage source 22 is opened when the sheet has been fed through the nip. However, it should be apparent that the cam 28 may be altered or replaced to provide different periods of switch actuation depending on the material of the sheet, the surface finish of the sheet and other factors.

Prior to energization of the electrostatic means 14 by actuation of the switch 23, the sheet of paper is supported in part on the peripheries of the moving cylinders 15, 16 and in part by a stationary support table 25. The table 25 preferably extends laterally from the cylinders 15 and 16 and includes a central slot 26 therethrough and which extends for at least the length of the cylinder. A smooth upper surface 24 of the table 25 is adapted to slidably receive and support a sheet of paper material which is fed onto the table from the right as viewed in the drawings. As shown in the drawings, the sheet of paper 11 is positioned on the surface 24 of the table so as to extend laterally across the table and is supported on opposite sides of the fold line by the upper peripheral portions of the cylinders. As previously described, the surfaces of the cylinders 15 and 16 are smooth so that when the sheet is supported thereon the surfaces 12 and 13 of the cylinders and the lower surface of the paper are in sliding engagement. The movement of the paper as it is fed onto the surfaces of the table is limited by a stop member 27. In order that the sheet 11 may be folded along any desired fold line, the stop member 27 is laterally adiustable on the table. The means for adjusting the stop 27 may be of any conventional design and has not been illustrated.

The operation of the sheet handling mechanism should be apparent from the above description. The stop 27 is adjusted to a position which will produce a crease in a sheet of paper at a desired location. The cylinders 15 and 16 are then rotated oppositely toward the nip 17. A sheet of paper is fed onto the table 25 and is supported in part by the surface 24 of the table, and in part by the rotating surfaces 12 and 13. After the sheet 11 abuts the stop 27, the switch 23 is actuated to close the circuit connecting the electrostatic means with the voltage source. When the circuit is closed, portions of the sheet 11 which are supported by the cylinders are electrostatically charged and are attracted to the surfaces 12 and 13, this attraction resists relative movement between the cylinders and the sheet so that the sheet is carried through the nip 17 on the surfaces of the cylinders and is discharged in folded form from the mechanism. As soon as the sheet is fed through the nip, the circuit is opened and another sheet may be fed onto the table and the process repeated.

It can now be seen that a sheet folding method and apparatus has been provided which is simple, effective to accurately fold sheets of material along a predetermined fold line, and capable of producing folded sheets of material at a high rate.

While the preferred embodiment of the present invention has been described in considerable detail the invention is not to be considered to be limited to the precise construction shown. My invention is to cover hereby all adaptations, modifications and uses of the material handling apparatus shown which come within the practice of those skilled in the art to which the invention relates and within the scope of the appended claims.

Having described my invention, I claim:

1. A method of folding sheet material along a predetermined fold line including the steps of providing a pair of movable surfaces, positioning a sheet of material on said surfaces, electrostatically securing spaced portions of said sheet to said surfaces on opposite sides of said predetermined fold line, and moving said surfaces with said spaced portions of said sheet secured thereto into facing relation to effect a folding of said sheet.

2. The method of folding sheet material as defined by claim 1 and further including the step of feeding a sheet of material to said surfaces and wherein the step of electrosatically securing said sheet to said surfaces includes the step of establishing an electric field adjacent said sheet in timed relation to the feeding of said sheetto said suraces.

3. The method of claim 1 wherein said surfaces comprise the peripheral surfaces of cylinder members and the step of moving said surfaces includes the step of rotating the cylinder member in opposite rotational directions toward a nip formed therebetween to move the sheet through the nip and effect folding thereof as the sheet moves through the nip.

4. The method of claim 1 wherein said step of positioning said sheet includes the step of adjusting a stop member relative to said surfaces whereby said sheet may be positioned to produce a fold line at a predetermined location on said sheet.

5. A sheet folding mechanism operable to fold a sheet of material along a predetermined fold line including a pair of movable surfaces, means for electrostatically securing spaced portions of said sheet on opposite sides of said fold line to said movable surfaces, and means for moving said surfaces with the spaced portions of the sheet secured thereto into facing relation so as to effect a folding of the sheet along said fold line.

6. A sheet folding mecahnism operable to fold a sheet of material along a predetermined fold line comprising a pair of cylinders defining a material folding nip therebetween, means for supporting a sheet of material adjacent said cylinders, eleotrostatic means for creating an attraction between spaced portions of said sheet on opposite sides of said fold line and said surfaces to detachably secure said portions on said surfaces, and means for rotating said surfaces in opposite rotational directions to thereby move said portions through said nip to effect a folding of said material.

7. The sheet folding mechanism of claim 6 wherein said electrostatic means includes a conductive element which is adapted to be electrically connected and disconnected from a voltage source and parts for establishing an electric field extending between portions of said surfaces and said electrostatic means.

8. The sheet folding mechanism of claim 7 wherein said electrostatic means is spaced from said cylinders and extends coaxially with said cylinders.

9. The sheet folding mechanism of claim 7 wherein said parts are ionizing needles for producing an electrostatic charge on spaced portions of said sheet, said portions being on opposite sides of said predetermined fold line.

10. The sheet folding mechanism of claim 6 wherein said electrostatic means includes switch means for energizing said electrostatic means and initiating said attrac- 3,362,705 5 6 tion between said portions of said sheet and said cylin- References Cited ders when said sheet is positioned on said surfaces. P

11. The sheet folding mechanism of claim 10 further UNITED ST,ATES ATENTS including means for operating said switch means in timed 1998337 4/1935 Spless 270*68 relation with the feeding of a sheet onto said surfaces. 5 2,493,410 1/1950 Lacour 270 68 12. The sheet folding mechanism of claim 6 wherein said means for supporting said sheet includes a stop mem- EUGENE CAPOZIO Pnmary Exammer' her for positioning the sheet relative to said surfaces. P. WILLIAMS, Assistant Examiner. 

1. A METHOD OF FOLDING SHEET MATERIAL ALONG A PREDETERMINED FOLD LINE INCLUDING THE STEPS OF PROVIDING A PAIR OF MOVABLE SURFACES, POSITIONING A SHEET OF MATERIAL ON SAID SURFACES, ELECTROSTATICALLY SECURING SPACED PORTIONS OF SAID SHEET TO SAID SURFACES ON OPPOSITE SIDES OF SAID 